Strip temperature control system

ABSTRACT

Individually controllable water sprays form a strip cooling zone at a runout table between the end of a hot strip finishing train and a coiler. The times required for successive sections of the strip to traverse the runout table (designated residence times) are calculated from a predetermined strip velocity-time profile. Using the residence times, the finishing train temperature and the desired coiling temperature, the number of sprays required to reduce the strip temperature from the finishing train temperature to the desired coiling temperature is determined as a function of the average velocity of the individual strip section. The distribution of the number of sprays thus determined is then calculated so as to provide a substantially constant rate of cooling which may be varied in accordance with individual requirements. The spray patterns are changed to coincide with the movement of the sections across the runout table.

United States Patent [1 1 [111 3,905,216 Hinrichsen Sept. 16, 1975 STRIP TEMPERATURE CONTROL SYSTEM Primary Examinerl ,owell A. Larson Assistant Examiner-E. M. Combs 51 t:EN.H"h ,Sh' td, [7 1 nven or mnc Sen c enec a y Attorney, Agent, or Fzrm-Arnold E. Renner; Philip L.

V Schlamp [73] Assignee: General Electric Company, Salem,

[57 ABSTRACT [22] Filed: Dec. 11, 1973 Individually controllable water sprays form a strip cooling zone at a runout table between the end of a [21] Appl' 423756 hot strip finishing train and a coiler. The times required for successive sections of the strip to traverse [52] US. Cl 72/13; 72/201 the runout table (designated residence times) ar 1- [51] Int. Cl. B21B 37/10; B21B 45/02 culated from a predetermined strip velocity-time pro- [58] Field Of Sear h 72/200, 13; file. Using the residence times, the finishing train tem- 148/ 153, 156, 157; 266/4 S, 6 S perature and the desired coiling temperature, the

number of sprays required to reduce the strip temper- [56] References Cited ature from the finishing train temperature to the de- UNTTED STATES PATENTS sired coiling temperature is determined as a function 2,851,042 9/1958 Spence 266 6 5 of FC F velocity of the individual Strip section- 3289 449 12/l966 OBden 72 /201 The distribution of the number of sprays thus deter- 3,300,19s 1/1967 Clumpner et a1 266/6 s mined is then Calculated SO as to Provide a Substan- 3,364,713 1/1968 Fukuda et al 72/201 tially constant rate of cooling which may be varied in 3,533,261 10/1970 Hollander et al. 72/201 accordance with individual requirements. The spray 3,58 ,1 0 /1 1 Gruver a] 72/201 patternsare changed to coincide with the movement 3,604,234 9/1971 Hinrichsen et a]... 72/201 X of the Sections across the runout 1 3,779,054 12/1973 Greenberger 72/201 X 22 Claims, 4 Drawing Figures AUXlLlARY INPUT COMPUTER 48 54 43 4 4, r f g 5 METAL PULSE PYRO PULSE SENSOR TAcH. METER TAcH. I s s 42 so 44 1 51 l l PYRO- LOAD PYRO- THlCKNESS METER SENSOR METER 1 GAGE l l 1 l I 31 l I 5% C) O O O (D J to 2,

5 0 U 5 I 5 14 wzzfczfi Q RL i i IL A i) PATENIEUSEPIEEH 3,905,216

sum 2 0f 2 y HG);

VELOCITY *0 in t2 13-245 TIME.

6 s F1623 D R 5 f 5 L no 2.: iris-nt t4 TIME g M FiG.4 D. (I)

o |.2 1.4 L6 L8 2.0

SPEED RATIO STRIP TEMPERATURE CONTROL SYSTEM BACKGROUND OF THE INVENTION The present invention relates generally to metal deforming and more particularly to the controlled cooling of a workpiece following a metal deforming operation.

In a tandem hot strip rolling mill, a relatively thick metal workpiece or slab having an initial temperature which may be as high as 2,200F is reduced to a relatively thin, elongated metal strip as it passes through a number of mill stands arranged in tandem along a mill table. By the time the strip leaves the last stand in the mill, heat losses caused by radiation, interstand cooling sprays and/or strip to roll conduction reduce the strip to a temperature in the range of l,400F to 1,750F depending upon the gauge of the strip. Upon leaving the last stand, the strip traverses a runout table on its way to a coiler where it is coiled and banded. The runout table serves as a cooling zone in which the temperature of the strip is reduced to a level suitable for the coiling operation. Depending upon the gauge of the strip, the desired coiling temperature may range from 850F to 1,500F. Because the runout table is normally from 300 to 500 feet long and because the speed at which the strip exits the last stand of the finishing train may be from 1,000 to 4,000 feet per minute, water sprays positioned above and below the runout table are usually needed to provide sufficient cooling.

Historically the water sprays were controlled manually. For example, an operator would observe the temperature of the strip by means of pyrometers located at the last stand of the finishing train and at the coiler. If

-temperature variations were observed, the operator would adjust the number of cooling sprays to correct the temperature error. Instrument lag and operator response time coupled with high speeds at which the strip traverses the runout table often kept the operator from altering the number of sprays at the time and place needed to properly correct the temperature deviation.

Automated control systems were then developed which performed essentially the same operation as was performed by the operator but at a higher speed. These systems, however, make no attempt to relate the spray to the area of temperature deviation. For example, if a higher than normal temperature were sensed at the entry to the runout table an increased number of sprays were immediately applied to the strip already on the .runout table regardless of the actual temperature of the strip in the area of the added sprays. Additional control systems were developed which attempted to control the cooling rate by spacing the potentially active sprays along the runout table and by successively activating sprays as the average strip speed varies.

The next step in the automation of runout table cooling was to relate the number of sprays utilized to specific sections of the strip as it traversed the table. In this system, the residence time of a section of strip was calculated according to the extant velocity-time profile for the strip based upon the residence time for each section and the initial and desired final temperatures of the strip. The number of sprays was calculated for each section. The sprays were then controlled to effect successive adjustments as the appropriate sections traversed the runout table. This system of control is described and claimed in US. Pat. No. 3,604,234, Temperature Control System For Mill Runout Table" by Eric N. Hinrichsen and Eugene R. Turk, issued Sept.

I4, 1971, assigned to the assignee of the present invention and which patent is specifically incorporated hereinto by reference.

As was stated, the control system of US. Pat. No. 3,604,234 calculated and turned on sprays with respect to individual sections of the strip as it traversed the table. These calculations were repeated for sections of approximately 50 to feet in length and the number of cooling sprays was adjusted as the actual finishing temperature and speed of the strip changed. Discrepancies between the measured and the desired temperatures were used to modify stored process models. The prior art systems did not, however, address themselves to the question of controlling the rate of temperature change as applied to defined strip sections through specified pattern changing. In this regard, it is Known that the metallurgical properties of hot rolled strip steel are dependent not only upon the steel chemistry, the temperature at which the last deformation takes place (the finishing temperature) and the temperature level at which the rolling process terminates (coiling temperature) but also upon the rate of temperature change with respect to time during the transition from finishing to coiling temperatures. Above 1630F steel has a purely face-centered crystal structure (austenitic) while below 1330F the crystal structure of steel is purely body-centered (ferritic). Between these two temperatures both forms, austenitic and ferritic, are present. The solubility of carbon in austenitic steel is higher than in ferritic steel. Two phenomenon take place when steel is cooled from the typical finishing temperature to the typical coiling temperature; the crystal structure changes from austenitic to ferritic and carbon is redistributed from a component in solution to a separate constituent known as pearlite. The size and distribution of the pearlite affects the metallurgical properties of the steel and is, in part, a function of the cooling rate.

SUMMARY OF THE INVENTION The present invention relates to the controlled cooling of a strip as it traverses a runout table. The residence time or time on the runout table is calculated for contiguous sections of the strip according to extant velocity-time profile for the strip. Based upon the residence time for each section and the initial and desired final temperatures of the strip, the number of sprays is calculated for each section. In order that the rate of cooling may be held substantially constant, the distribution of the number of sprays is then determined. The sprays are then controlled to effect successive pattern adjustments as the individual sections traverse the runout table. The rate of cooling may be adjusted by operator intervention or by modification of stored constants.

DESCRIPTION OF THE DRAWINGS While the specification concludes with claims particularly pointing out and distinctly claiming what is regarded as the present invention, details of a preferred embodiment of the present invention may be more readily ascertained from the following description when read in conjunction with the accompanying drawings in which:

FIG. 1 is a simplified view of a hot strip mill in which the invention finds use;

FIG. 2 is a representative velocity-time profile for a strip traversing a runout table;

FIG. 3 is a graph of the integral with respect to time of part of the velocity-time profile in FIG. 2; and,

FIG. 4 is a graph showing a typical relationship between the ratio of sprays required with respect to the increase in strip speed.

DETAILED DESCRIPTION In a hot strip mill, the initial reductions in the thick ness of a metal slab are taken in a set of tandem mill stands known collectively as a roughing train. FIG. 1 shows, in greatly simplified form, the last stand R, of a roughing train along with other components in a hot strip mill. As the slab emerges from the stand R it moves across a mill table 20 toward a finishing train 22 consisting of mill stands F1, F2, F3, F4 and F arranged in tandem. The final reductions in thickness are taken in the finishing train 22 to produce a metal strip which may be 1,000 or more feet in length. As the strip emerges from the last stand F5 in the finishing train 22 it traverses a cooling or runout table 24 before being wound by a coiler 26. Strip tension during coiling operation is maintained by a pair of pinch rolls 28 and 30 located at the coiler end of the runout table 24. The strip temperatures at which the coiling operation may be carried out are considerably lower than the normal strip temperatures at the last stand of the finishing train 22. A number of individually controlled cooling sprays, one of which is designated by the numeral 32, are located above and below the runout table to form a cool ing zone 36 in which the strip is water-cooled to the proper temperature for coiling. The cooling zone 36 is typically in the order of from 300 to 500 feet long and may be made up of to 100 individual sprays located above the runout table with approximately the same number being located below the runout table 24.

The speed of the strip emerging from the finishing train 22 is not constant but may vary as the finishing train is accelerated and decelerated to increase productivity or to maintain a constant finishing train temperature whenever possible while remaining within safe operating limits. To cool each section of the strip to a relatively constant temperature by the time a section of the strip reaches the coiler 26, the amount of cooling water that is applied to the strip in the cooling Zone 36 is adjusted. According to the preferred embodiment of the present invention, the volume of water delivered by each spray remains constant but the number of sprays is adjusted and their distribution is varied so as to not only maintain a constant coiling temperature but to also control the rate at which the strip is cooled.

The temperature of the strip as shown in FIG. 1 is monitored by three different pyrometers. A first pyrometer 42 is located at the exit side of the last stand R, of the roughing train. A second pyrometer 44 is located between the penultimate stand F4 and the last stand F5 in the finishing train 22 whereas a third py' rometer 46 is located at the entry to the coiler 26. The temperature sensed by the pyrometer 42 is one factor in determining the initial spray pattern. The tempera ture feedbacks from the pyrometers 44 and 46 may be used to modify spray patterns for a strip currently being cooled and to adapt stored data to improve the control of cooling of subsequent strips.

The ends of the strip are detected by suitable means which in FIG. 1 are illustrated by a metal sensor 48 located above the mill table 20, a load sensor 50 located in stand F I and a thickness gauge 22 located between stand F5 and the cooling zone 36. Detecting the ends of the strip are secondary functions for the load sensor 50 and the thickness gauge 52, their respective primary functions being measurement of roll separating forces at stand F l and measurement of the final gauge of a strip. A first pulse tachometer 54 mechanically coupled to one of the rolls in stand F5 monitors the velocity of and the elapsed distance traveled by the strip as it emerges from the finishing train 22. A second pulse tachometer 56 mechanically coupled to pinch roll 28 may be used to monitor the travel and velocity of the strip after the tail end of the strip leaves the stand F5 and the pulse tachometer 54 is no longer effective. Outputs from the described sensors are applied to a computer 40 which has an auxiliary input 41 and an output 43 to the sprays in the cooling zone 36. It should be pointed out that the tachometers are included as illustrative of the function to be provided; that is, speed and strip section position as will be more fully explained hereinafter. It is to be realized, however, because the strip follows a velocity profile established by a process model stored in the computer memory, that these same determinations can be made without the benefit of a physical device such as the illustrated tachometers.

The speeds at which the finishing train 22 operates determine the strip velocities until the tail end of the strip leaves the stand F5 at which time strip velocity control passes to the coiler 26. In either situation, the speeds are determined by the properties of the strip according to predetermined relationships which, taken in chronological sequence, establish a velocity-time profile which may be of the type illustrated in FIG. 2. (FIG. 2 is actually more complex than many velocity-time profiles which merely provide an acceleration to a peak and then a deceleration to a lower velocity. The form of the profile does not, however, change the application of the present invention.) FIG. 3 is the time integral of a portion of the profile of FIG. 2. FIGS. 2 and 3 are conceptually identical to those numbered figures shown and described in the aforementioned US. Pat.

No. 3,604,234. For a complete description of these two figures, reference is made to that patent. Very briefly, however, FIG. 2 shows the relationship of a typical strip as it is processed through the finishing train 22 across the runout table 35. As shown in that figure, at time t the head end of the strip leaves stand F5 and enters the runout table at a velocity indicated as V which is termed the lower base velocity. The strip then moves at the V speed until the time shown as t, at which time the head end enters the coiler 26. Under the preestab lished program for the strip of material being processed, the strip will then accelerate at a predetermined rate .under the control of the computer 40 until it reaches a value shown at t and designated V for the upper base of velocity.

When the strip reaches its highest speed, it will remain at that speed until such time as the tail end of the strip leaves the first stand Fl of the finishing train, shown at A deceleration period then will commence under computer control to a velocity indicated as V which is a maximum safe speed at which the tail end may leave the final stand F5 of the finishing train. At time t,, a further deceleration will be programmed through the computer until time 1 at which time the tail end of the strip reaches the coiler and the strip has been fully processed. FIG. 3, as is fully explained in the aforementioned US. Pat. No. 3,604,234, is the integral of a portion of the velocity-time profile of FIG. 2 and by the use of this graph the residence times of any par ticular section of the strip on the runout table may be determined. As shown in FIG. 3, the relation of a specified distance on the vertical axis to the time scale on the horizontal axis provides the residence time of a particular section on the runout table. Also, as set forth in the above-identified patent, the time at which a particular strip section is located on the runout table and the location on that runout table may be identified through the utilizations of the pulse tachometers 54 and 56. As there explained, by knowing the number of pulses produced by the tachometers 54 or 56 per foot of strip movement, the distance in feet between a particular section and the head end of the strip, the section can be identified as being at the beginning of the runout table or at any point on the runout table in accordance with the count of a pulse tachometer.

With knowledge of the residence times of the individual strip sections on the runout table and of the physical characteristics of the steel being processed, the number of sprays required to reduce the temperature of the strip from the finishing train temperature to the desired coiling temperature can be determined for the upper base speed V and the lower base speed V These numbers are designated respectively N and N and their determination is set forth fully in the aforementioned US. Pat. No. 3,604,234.

In accordance with the present invention, a determination is also made as to the distribution of the number i of sprays N and N, to achieve a constant rate of tem- Thus, for example, in a runout table having a total number of sprays equal to 100, if N,- were equal to 20, then SIU would be equal to 5 and every fifth spray; that is, sprays 5, 10, 15, etc., would be turned on when the strip is traversing the table at its upper base speed. If SIU were equal to 4.5, then an alternating pattern of successive fourth and fifth sprays would be activated at the upper base speed.

It is, of course, recognized that the term SI U will not in all cases turn out to be either an integer or a half-step between integers. If a high degree of accuracy is not required for controlling the rate of cooling, then SIU may be rounded to the nearest one-half and the pattern determined in the above manner. If a higher degree of accuracy is required, thenthe spray pattern may be determined by the expression:

In this equation, N is the sequential number of the spray and R is the remainder from a previous calculation for which K was larger than the next whole number. In applying this expression, the computer makes successive calculations for each spray. Whenever K is equal to or larger than the next whole number from the preceding calculation, that particular spray will be turned on. The remainder from a calculation designating a spray to be turned on is then saved and used as the R term in each subsequent calculation until K reaches the next larger whole number designating the next spray which will be turned on. At the beginning of the calculation R is set equal to zero. (It should be further noted that in the event it is desired to have the first spray turned on in each instance, zero may be considered the first whole number in which case spray number 1 would be added to the above spray pattern. This increases the total number of sprays to 21 but does not vary the concept of the present invention. This same option is applicable to similar calculations described hereinafter.) Thus, by this system, a more precise spray pattern may be established to provide the cooling rate than by the rounding off method and a more accurate cooling rate will be achieved. As an example of this typeof selection, if SIU were equal to 4.7, it may be calculated that the spray pattern for a spray runout table would include sprays 5, l0, l4, 19, 23, 28, 33, 38, 42, 47, 52, 56, 61, 66, 71, 75, 80, 84, 90, 94 and 98. Regardless of which of the two methods is used to establish the spray pattern for the upper speed N the computer stores in its memory an indication of which sprays will be turned on for the upper base speed.

The next step to be accomplished is the calculation of the spray pattern corresponding to the lower base velocity V which will give the same rate of cooling as is achieved at the upper base velocity V The low speed spray pattern is accomplished in a manner very similar to that as done with respect to the high speed pattern by first determining the spray interval which is designated SIL. This interval is determined by the expression:

Continuing with the example presently being used, it will be remembered that N was determined to be 20 providing a value of SI U equal to 5. It will be assumed that this upper base speed number corresponds to a velocity of 1500 feet per minute, that the lower base velocity is 1000 feet per minute and that the calculation made for the value of N, was equal to 10. SIL will, therefore, be equal to 6.667. With this value of SIL, either of the two methods of selecting which sprays to be turned on may be selected. That is, SIL may be rounded off to 7 in which case sprays numbers 7, 14, 21, etc. would be turned on up to the total number of sprays equaling to N, to provide 10 sprays space a distance of 7 apart. If a more precise pattern is required, then the spray pattern is determined in accordance with the equation:

N K SIL R which equation is identical to that set forth above with the exception of the substitution of SIL for SIU. Employing the value SIL 6667, it may be seen that sprays 7, 14, 20, 26, 33, 40, 47, 54, 60 and 66 would be turned on. Once again, the arbitrary choice of whether or not to turn on the first spray would be made and the additional decision would have to be made as to whether, in this case, to provide or 11 sprays. Normally, 1O sprays would be selected and thus by the previous calculation the last spray to be turned on in this spray pattern would be spray number 60. The sprays for the lower base velocity selected by one of the two methods is now stored in the computer memory and is available for use. It is noted, however, that the patterns thus far determined are only valid for the two speeds the lower base speed and the upper base speed.

In accordance with the present invention spray patterns are now determined for intermediate strip speeds between V and V Two methods of achieving this are readily available. The first of these methods employs the selection of intermediate values for the spray interval between SIL and SI U and the relating of these values to their appropriate strip velocities. The second method is to select specific velocity steps between V and V and to determine the spray interval required for each of these velocity steps. Theoretically, of course, there is an infinite number of possible steps and a judicious decision as to the number used must be made weighing the desire for accuracy against the practicality of the situation. In either case the required unknowns may be calculated from the expression:

SII= SIH wherein S11 is the spray interval between sprays for the intermediate pattern, V, is the intermediate speed and N, is equal to the number of sprays required for the intermediate speed V,. v

It has been found through experience that the relationship existing between the number of sprays required and the speed is not a linear function. For exam ple, an increase in speed of 40 percent will require an increase in the number of sprays of approximately 70 percent. This relationship is illustrated in the graph of FIG. 4 which is an empirically derived curve showing the relationship between the ratio of number of sprays and the speed ratio. This curve has been found to be essentially true for those steels processed by rolling mills to which the present invention is applicable. While the exact relationship may vary slightly from material to material and thickness to thickness, the curve is basically accurate and may, if desired, be modified based upon experience in an actual installation.

Continuing with the explanation in the form of the present example, it will be assumed that the intermediate stcps between SIU and SIL will be based upon velocity increments between V, 1000 feet per minute and V,- 1500 feet per minute and that there will be four increments each corresponding to a change of 100 feet per minute. Referencing now FIG. 4 it is seen that at a speed of l 100 feet per minute (speed ratio of 1.1 the spray ratio is about 1.12 which corresponds to a number of the sprays equal to approximately 11.2. Similarly, the spray ratios for the velocities of 1200, 1300 and 1400 feet per minute are 1.25, 1.44 and 1.7 corresponding respectively, to 12.5, 14.4 and 17 sprays for the intermediate speeds N Utilizing these values the value SII may be calculated in each case and once again using the basic expression the spray pattern can be determined. if steps in the spray interval were selected, the velocities at which the spray intervals will be applicable may be derived from the same chart by finding the appropriate spray ratio on the vertical axis and relating that ratio to the speed ratio and the lower base speed V However derived, these intermediate spray patterns are stored in the computer memory and related to their appropriate strip velocities.

With these parameters now stored in the computer memory, the head end of the strip is processed through the finishing stands to the coiler and calculations are made for the leading edge of each strip section to see whether or not the average speed of that particular section will exceed the speed for the next higher spray pattern. The sprays are under the control of the computer so as to be related to a particular strip section in sub stantially the identical manner as is set forth in US. Pat. No. 3,604,234, the difference being that instead of a contiguous group of sprays being applied the sprays are distributed more fully along the length of the runout table in order to not only control the total amount of cooling but also the rate of cooling.

The description thus far has provided a system which provides a substantially constant rate of cooling as the strip progresses over the runout table. it will be remembered from US. Pat. No. 3,604,234 that adaptive feedback is provided to change the model stored in the computer in the event that observed parameters do not agree with those anticipated by the model. For example, if the coiling temperature were higher than anticipated, the adaptive feedback would serve to increase N and thus provide a greater number of sprays for the next strip. In the present invention, this adaptive feedback would also result in different spray patterns for subsequent strips. This same concept of adaptive feedback may be utilized to correct and/or change the rate of cooling from that prescribed by the model. For example, were it observed, by either the operator or by some sensor, that the rate of cooling is in error, it could be changed by adaptive feedback procedures. This feature or the ability to change the rate of' cooling may be expressed by the expression:

wherein C is a correction constant. If it were determined that the rate of cooling were too high, indicating that the spray interval is too small, the constant C would be made slightly larger than 1 so as to increase the value of SIH which would, in turn, affect all subse quent calculations for the intermediate and low speed spray patterns. Similarly, if the rate of cooling were too low, the constant C would be made slightly less than 1 thus decreasing the spray interval SIH and hence all other speed intervals. It is recognized that the incorporation of this feature requires certain adjustments to be made in the earlier determinations. Specifically, it is readily seen that if a constant C greater than 1 is permitted, the value of SIH will increase and hence there than the actual total number of sprays available. For

example, in the illustrative embodiment being used the actual total number of sprays is 100 and N was used as 100. Adjustment would be achieved by selecting a lesser number, say 90, for N in all calculations.

The aforementioned functions were described with respect to the upper sprays only and identical type calculations would be performed and identical type operations performed with respect to the lower sprays which are independently controlled in the preferred embodiment of this invention so that a higher degree of resolution can be achieved. The independent switching will normally effect a lesser disturbance than if both were switched at the same time. This concept may be assured by selecting different relative velocities for switching the upper and lower sprays such that the upper sprays are assured of switching at a different time than the lower sprays.

.present invention would notice two effects; the length of the spray zone would increase with the strip speed and, during the time required for the complete rolling of a strip, one or more pattern changes would ripple down the spray pattern from the finish mill towards the cooler. These ripples would be the changing of the spray patterns as the sections traverse the table and as the spray patterns were changed in accordance with the change in strip velocity.

Thus, it is seen that there has been shown and de' scribed a system employed in the deformation of metal for providing controlled cooling of the strip as it leaves a finishing mill and proceeds towards the coiler. This system not only maintains constant cooling but also provides a controllable rate of cooling throughout the runout process.

While there have been shown and described what are at present considered to be the preferred embodiments of the invention, modifications thereto will readily occur to those skilled in the art. It is not desired, there fore, that the invention be limited to specific arrangements shown and described and it is intended to cover in the appended claims all such modifications as fall within the true scope and spirit of the invention.

What is claimed is:

1. For use in a rolling mill including a finishing train, a runout table with a zone of controllable cooling sprays and a coiler, the method of cooling a strip at a predetermined rate as the strip traverses the runout table comprising the steps of:

a. determining the time at which each of contiguous sections of strip is situated at predetermined loca- 5 tions along the runout table;

b. calculating, in accordance with prescribed formulas, for each of said contiguous sections, an individual number and an individual, substantially uniform spacing of sprays required to cool each section from a finishing train temperature to a desired coiler temperature at a prescribed rate and as a function of the average velocity of the section as it traverses the runout table; and,

c. selectively rendering said sprays operative in accordance with the calculated number and spacing at the determined time for each of said sections as they are successively situated along the runout table.

2. The invention in accordance with claim 1 wherein the spacings of sprays are calculated for prescribed increments in strip velocity.

3. The invention in accordance with claim 1 wherein the spacings of sprays are preselected and are rendered effective in response to a determination that a section will reach an average velocity associated with that pattern.

4. The invention in accordance with claim 1 further including the step of adjusting the number and the spacings of sprays in response to an observed deviation in actual cooling from a desired cooling.

5. For use in a rolling mill including a finishing train, a runout table, a zone of controllable cooling sprays and a coiler, the method of cooling a strip at a predetermined rate as the strip traverses the runout table comprising the steps of:

a. determining the time at which each of contiguous section of strip is situated at predetermined locations along the runout table;

b. calculating the number of sprays necessary to reduce the strip temperature from that existing at the time of exit from the finishing train to a desired coiler temperature for both the upper and lower speeds anticipated for the strip;

c. calculating, in accordance with prescribed formulas, individual substantially uniform spray spacing patterns to achieve a substantially uniform rate of strip cooling for each of said upper and lower speeds;

cl. calculating an additional individual number of sprays and an additional substantially individual uniform spray spacing pattern, in accordance with prescribed formulas, to achieve a substantially uniform rate of strip cooling corresponding to a strip speed intermediate said upper and lower speeds; and,

e. selectively rendering said sprays operative in ac cordance with said numbers and said spray spacing patterns in response to a determination that a section of strip will have a related average speed as it traverses the runout table.

6. The invention in accordance with claim 5 wherein the spray spacing pattern for the upper base speed is determined by spacing the number of sprays deter mined for that speed along substantially the total length of the spray zone.

7. The invention in accordance with claim 5 wherein the spray spacing pattern for the upper base speed is defined by the expression:

. M N .SIH-

in which:

SIH the interval between sprays for the upper base speed N A the total number of sprays within the spray zone N the number of sprays required to effect the specified cooling at the upper base speed.

8. The invention in accordance with claim 7 wherein all additional spray spacing patterns are determined with respect to the spray spacing pattern determined for the upper base speed in accordance with a prescribed relationship defined by the expression:

SI( X) the interval between sprays for the pattern being determined SIH the interval between sprays as determined for the upper base speed N the number of sprays required to effect the specified cooling at the upper base speed N( X) the number of sprays required to effect the specified cooling at a speed other than the upper base speed V(X) the average speed of the strip section being cooled V the upper base speed.

9. The invention in accordance with claim 8 wherein the applicable individual sprays for each of the additional spray spacing patterns are determined in accordance with the relationship:

R a remainder retained from a previous calculation for which K was a whole number larger than a preceding whole number.

and wherein:

the value of K reaching a whole number larger than that of a preceding calculation determines that spray N will be turned on.

10. The invention in accordance with claim 5 further including the step of adjusting the number of sprays and the spray spacing pattern in response to an observed deviation in actual cooling from a desired cooling.

1 1. The invention in accordance with claim 7 further including the step of selectively adjusting the number of sprays spacing and the spray pattern to adjust the rate of Cooling by adjusting the value of SIH by a constant C as defined by the expression:

12. The invention in accordance with claim 11 wherein the selective adjustment is made in response to an observed deviation of the actual cooling rate from a desired cooling rate.

13. The invention in accordance with claim 11 wherein the selective adjustment is made under operator control to effect a change in the metallurgical properties of the strip being processed.

14. The method of cooling a strip as set forth in claim 5 in which there is included a second zone of cooling sprays, the first zone being located above the strip and the second zone being located below the strip wherein each of the defined steps is separately executed for both of the zones.

15. The invention in accordance with claim 14 wherein the additional spray spacing pattern is established with respect to a first strip speed for the spray zone located above the strip and for a different speed with respect to the spray zone located below the strip.

16. The invention in accordance with claim 5 wherein plural calculations of individual numbers of sprays and of spray spacing patterns are made for plural corresponding related average strip speeds intermediate said upper and lower speeds.

17. The invention in accordance with claim 16 wherein the spray pattern for the upper base speed is determined by spacing the number of sprays determined for that speed along substantially the total length of the spray zone.

18. The invention in accordance with claim 16 wherein the spray spacing pattern for the upper base speed is defined by the expression:

in which:

SIH the interval between sprays for the upper base speed N the total number of sprays within the spray zone N the number of sprays required to effect the specified cooling at the upper base speed.

19. The invention in accordance with claim 18 wherein all additional spray patterns are determined with respect to the spray spacing pattern determined for the upper base speed in accordance with a prescribed relationship defined by the expression:

N(X) the number of sprays required to effect the N K- S, R

wherein:

N the sequential number of the spray within the zone R a remainder retained from a previous calculation for which K was a whole number larger than a preceding whole number and wherein:

the value of K reaching a whole number larger than that of a preceding calculation determines that spray N will be turned on.

21. The invention in accordance with claim 16 further including the step of adjusting the number of sprays and the spray spacing pattern in response to an observed deviation in actual cooling from a desired cooling.

22. The invention in accordance with claim 18 further including the step of selectively adjusting the number of sprays and the spray spacing pattern to adjust the rate of cooling by adjusting the value of SIl-l by a constant C as defined by the expression:

r Page 1 of 2 UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3,905,216

DATED I September 16, 1975 INVENTOR( 1 Eric N. Hinrichsen It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below: Column 2 line 16 cancel "Known" and substitute -known-.

Column 4, line 2, cancel "22" and substitute 52-. line 27, cancel "V and substitute V Column 5 Column 6, line 64, cancel "space" and substitute spaced-. Column 7, line 40, cancel "SIH" and substitute SIU. Column 8, line 60, cancel "SIH" and substitute SIU.

line 67, cancel "SIH" and substitute SIU. Column 9, line 4, cancel "SIH" and substitute SIU. line 9, cancel "SIH" and substitute SIU. line 11, cancel "SIH" and substitute SIU. r Column ll, line 5, cancel "SIH" and substitute SIU. line 10, cancel "SIH" and substitute SIU. 9 line 24, cancel "SIH" and substitute SIU. r line 29, cancel "SIH" and substitute SIU. line 45, cancel "SIH" and substitute SIU. line 53, after "number" delete the period. line 65, after "sprays" delete "spacing" and after "spray" insert spacing. line 66, cancel "SIH" and substitute SIU. Column 12, line 1, cancel "SIH" and substitute SIU. line 41, cancel "SIH" and substitute SIU. line 46, cancel "SIH" and substitute SIU. r line 56, cancel "SIH" and substitute SIU. line 64, cancel "SIH" and substitute SIU.

Page 2 of 2 PATENT NO.

DATED TNVENTOHS) 1 September 16,

Eric N. Hinrichsen It is certified thaf error appears in the above-identified patent and that said Letters Patent are hereby correcied as shown below:

Column 13, Column 14,

line 11, line 13, line 16,

and substitute SIU. and substitute SIU. and substitute SIU.

IISIHII IISIHII IISIHII cancel cancel cancel 

1. For use in a rolling mill including a finishing train, a runout table with a zone of controllable cooling sprays and a coiler, the method of cooling a strip at a predetermined rate as the strip traverses the runout table comprising the steps of: a. determining the time at which each of contiguous sections of strip is situated at predetermined locations along the runout table; b. calculating, in accordance with prescribed formulas, for each of said contiguous sections, an individual number and an individual, substantially uniform spacing of sprays required to cool each section from a finishing train temperature to a desired coiler temperature at a prescribed rate and as a function of the average velocity of the section as it traverses the runout table; and, c. selectively rendering said sprays operative in accordance with the calculated number and spacing at the determined time for each of said sections as they are successively situated along the runout table.
 2. The invention in accordance with claim 1 wherein the spacings of sprays are calculated for prescribed increments in strip velocity.
 3. The invention in accordance with claim 1 wherein the spacings of sprays are preselected and are rendered effective in response to a determination that a section will reach an average velocity associated with that pattern.
 4. The invention in accordance with claim 1 further including the step of adjusting the number and the spacings of sprays in response to an observed deviation in actual cooling from a desired cooling.
 5. For use in a rolling mill including a finishing train, a runout table, a zone of controllable cooling sprays and a coiler, the method of cooling a strip at a predetermined rate as the strip traverses the runout table comprising the steps of: a. determining the time at which each of contiguous section of strip is situated at predetermined locations along the runout table; b. calculating the number of sprays necessary to reduce the strip temperature from that existing at the time of exit from the finishing train to a desired coiler temperature for both the upper and lower speeds anticipated for the strip; c. calculating, in accordance with prescribed formulas, individual substantially uniform spray spacing patterns to achieve a substantially uniform rate of strip cooling for each of said upper and lower speeds; d. calculating an additional individual number of sprays and an additional substantially individual uniform spray spacing pattern, in accordance with prescribed formulas, to achieve a substantially uniform rate of strip cooling corresponding to a strip speed intermediate said upper and lower speeds; and, e. selectively rendering said sprays operative in accordance with said numbers and said spray spacing patterns in response to a determination that a section of strip will have a related average speed as it traverses the runout table.
 6. The invention in accordance with claim 5 wherein the spray spacing pattern for the upper base speed is determined by spacing the number of sprays determined for that speed along substantially the total length of the spray zone.
 7. The invention in accordance with claim 5 wherein the spray spacing pattern for the upper base speed is defined by the expression:
 8. The invention in accordance with claim 7 wherein all additional spray spacing patterns are determined with respect to the spray spacing pattern determined for the upper base speed in accordance with a prescribed relationship defined by the expression:
 9. The invention in accordance with claim 8 wherein the applicable individual sprays for each of the additional spray spacing patterns are determined in accordance with the relationship:
 10. The invention in accordance with claim 5 further including the step of adjusting the number of sprays and the spray spacing pattern in response to an observed deviation in actual cooling from a desired cooling.
 11. The invention in accordance with claim 7 further including the step of selectively adjusting the number of sprays spacing and the spray pattern to adjust the rate of cooling by adjusting the value of SIH by a constant C as defined by the expression:
 12. The invention in accordance with claim 11 wherein the selective adjustment is made in response to an observed deviation of the actual cooling rate from a desired cooling rate.
 13. The invention in accordance with claim 11 wherein the selective adjustment is made under operator control to effect a change in the metallurgical properties of the strip being processed.
 14. The method of cooling a strip as set forth in claim 5 in which there is included a second zone of cooling sprays, the first zone being located above the strip and the second zone being located below the strip wherein each of the defined steps is separately executed for both of the zones.
 15. The invention in accordance with claim 14 wherein the additional spray spacing pattern is established with respect to a first strip speed for the spray zone located above the strip and for a different speed with respect to the spray zone located below the strip.
 16. The invention in accordance with claim 5 wherein plural calculations of individual numbers of sprays and of spray spacing patterns are made for plural corresponding related average strip speeds intermediate said upper and lower speeds.
 17. The invention in accordance with claim 16 wherein the spray pattern for the upper base speed is determined by spacing the number of sprays determined for that speed along substantially the total length of the spray zone.
 18. The invention in accordance with claim 16 wherein the spray spacing pattern for the upper base speed is defined by the expression:
 19. The invention in accordance with claim 18 wherein all additional spray patterns are determined with respect to the spray spacing pattern determined for the upper base speed in accordance with a prescribed relationship defined by the expression:
 20. The invention in accordance with claim 19 wherein the applicable individual sprays for each of the additional spray spacing patterns are determined in accordance with the relationship:
 21. The invention in accordance with claim 16 further including the step of adjusting the number of sprays and the spray spacing pattern in response to an observed deviation in actual cooling from a desired cooling.
 22. The invention in accordance with claim 18 further including the step of selectively adjusting the number of sprays and the spray spacing pattern to adjust the rate of cooling by adjusting the value of SIH by a constant C as defined by the expression: 